EDITOR’S NOTE — Organizers of the Farm Press Peanut Profitability Award have reviewed production data from previous winners to arrive at a “Top 10 Keys to Peanut Profitability.” This list of successful production practices has been presented in descending order in Southeast Farm Press and on this website, with sponsorship provided by DuPont Crop Protection. The Peanut Profitability Awards, based on production efficiency in whole-farm situations, is entering its 13th year and is administered by Marshall Lamb, research director for the National Peanut Research Laboratory, and his staff.

But without water, the success of each key is significantly reduced and that is why irrigation comes in at No. 1 in the list of Top 10 Keys to Peanut Profitability.

Marshall Lamb, director of the USDA National Peanut Laboratory, says irrigation increases peanut yield by about 30 percent on a 10 year average, and even drastically higher in drought years like those experienced in all peanut producing regions in recent years.

“Managing irrigation with Irrigator Pro will add at least 300 pounds per acre in yield for irrigated producers,” he says. “This is why so many past Peanut Profitability and high yield winners use Irrigator Pro — including one of last year’s winners, Kreg Freeman, and a host of others.”

The availability of moisture for peanuts is critical at key times in the growing season for maximum yield and to reduce stress that can affect both yield and quality. Without irrigation, during the past three years many growers across the peanut-producing belt in the U.S. simply couldn’t plant peanuts because of a lack of soil moisture.

This year, for example, Luray, S.C., growers Bud and Corrin Bowers say they couldn’t plant cotton or peanuts on time because they didn’t have moisture in some fields. Fortunately, they have irrigation on some of their peanut land and could apply enough water to plant.

Unfortunately, about a third of their peanut crop this year is on new ground, which for the most part is not irrigated.

“Because of a lack of moisture at planting time, this has been one of the most frustrating times I’ve had in farming,” says Bud Bowers. “We got backed up on planting cotton, which got us backed up on planting peanuts — without irrigation we would have been in a bigger mess.”

Like so many growers across the Southeast and Virginia-Carolina belts, the Bowerses have to contend with herbicide-resistant weeds, particularly glyphosate-resistant Palmer amaranth (pigweed).

In the past, growers dealt with virtually every weed problem with glyphosate pre-plant and an over the top early season application of the same material, plus one or two others to control the few grasses and weeds not adequately controlled by glyphosate.

Now, it is almost standard practice among peanut growers go back to a pre-glyphosate regimen, applying pre-plant herbicides to manage resistant weeds and reduce the amount of glyphosate used in order to lower the risk of further resistance problems.

Water activated herbicides

Most older-generation herbicides used at planting time have to be water activated.

Longtime University of Georgia Extension Peanut Specialist John Baldwin probably said it best when talking about the use of moisture-activated herbicides: “If it don’t rain, it don’t matter.” Without proper moisture, it won’t matter whether the herbicides are there or not.

Irrigation is often a poor substitute for Mother Nature’s water, but in some cases, it can be a better way to water-in herbicides. The labels of several herbicides state that as long it is incorporated within three weeks, the herbicide will be effective. The best way to get full activation is to have one rain event that provides all the water needed to activate the herbicide.

Most water-activated herbicide labels also say these materials need water within 21 days. Many times, growers think they need a cumulative amount of rainfall within that three-week period to activate the herbicide. Research indicates that may be a recipe for failure.

Peanuts are predominantly grown on sandy soils. If these soils are allowed to dry after a rain, or after a low rate of irrigation, and are followed between similar showers or low levels of irrigation, the herbicide will bind tightly to the top layer of the soil without adequately moving through the soil.

By applying adequate irrigation water at planting, growers can insure these type herbicides will keep their peanuts clean for the first few weeks of growth.

Irrigation is an expense, and it can be significant in some parts of the country. To produce peanuts profitably, growers must manage irrigation just as they manage other crop inputs. Balancing the irrigation cost checkbook is equally as important as justifying the use of fertilizer, fungicides and other peanut inputs.

Just like money in the bank, the water bank account can fall quickly when things don’t go as planned. To manage the water bank, the grower has to measure the amount of moisture in the soil.

Growers irrigate crops to maximize yield. To maximize yield, the grower has to maximize evapotranspiration. To accomplish those goals, the farmer has to measure water accurately.

Evapotranspiration (ET) is the transport of water into the atmosphere from surfaces, including soil (soil evaporation), and from vegetation. Soil and vegetation are the most important contributors to evapotranspiration.

Other contributors to evapotranspiration may include evaporation from wet canopy surface and evaporation from vegetation-covered water surface in wetlands.

The evaporation component of ET is comprised of the return of water back to the atmosphere through direct evaporative loss from the soil surface, standing water (depression storage), and water on surfaces (intercepted water) such as leaves and/or roots.

Transpired water is that which is used by vegetation and subsequently lost to the atmosphere as vapor.

There are a number of monitors that can be used to determine exactly how much irrigation water peanut plants need. These irrigation water guides are available from Extension specialists in any peanut-producing state and from any irrigation equipment dealer.

Corrin Bowers in South Carolina came back to his father’s farm armed with a degree in engineering from the University of South Carolina and valuable industry experience with precision technology. He has helped develop a highly successful system of monitoring soil and plant moisture and applying irrigation water as needed.

Combination of two older programs

“We use a program called TCH20 that is a combination of two older programs,” he says.

“We put sensors at 8, 16 and 24 inches in the soil. The system has a data logger that records 24 hours a day, seven days week. I can go to the field with my computer and hook it up to the data logger or as long as I have a clear line of sight I can do it with a radio connection.

“After the crop is planted, I go in every morning and get a histogram of what the water is doing. I can tell what the plant available water and soil moisture are each day. It’s a highly evolved computer program that allows me to be a better farmer — I know more about our crop than we used to know.

“We are now watering our crops based on when the plants really need water. It takes out all the guesswork of looking at a crop and trying to determine when to irrigate and when not to irrigate,” Bowers says.

Another system of irrigating peanuts was recently developed by former USDA-National Peanut Research Laboratory Scientist Wilson Faircloth. The system developed in Georgia and Texas is called primed acclimation.

It is the intentional but regulated use of mild stress to change plant water use. Faircloth says the concept is similar to someone getting a flu shot, which actually exposes them to a mild case of the flu. When they come in contact with the same flu virus, their body is prepared for it and knows how to fight it.

“With primed acclimation, you are exposing the plant to intentional, regulated drought stress so it changes the physiology of the plant and changes its growth habits, such as causing it to have deeper rooting,” Faircloth says.

The newest version of Irrigator Pro, the expert system developed to help producers make decisions about their operations, now includes the concept of primed acclimation as an option for irrigation management, plus many other changes.

How much benefit growers get from proper use of irrigation varies significantly from one farm to another and from one year to another.

In drought years, laced with intense heat and humidity, irrigation can make a 2,000 pound per acre difference in yield. In addition to the yield increase, having water can also significantly reduce the incidence of aflatoxin and diseases that can further cut peanut profitability.

Most growers agree that in years that are within 20 year norms in heat and rainfall, irrigation consistently increases yields by 1,000 pounds per acre.

“Irrigation is the key factor in sustaining farm incomes and minimizing weather associated risks,” Lamb says. “This is true not just for peanuts, but for the crops we rotate with as well.

“We need to expand and protect irrigated acres. That’s why programs such as the Alabama Irrigation Initiative (and similar programs) are vital to our future.”

(An introduction to this series of keys to peanut profits can be found here. Keys No. 10 and No. 9 can be found here. No. 8 and No. 7 are here. Cost management, efficient water use two more keys to peanut profits came in at No. 6 and No. 5. Disease control ranked No. 4 and that information can be found here. The No. 3 key was listed as proactive farm management. That information is available here. Finishing in the No. 2 position was crop rotation. Read that article here).